Method of determining measurement-point position data and device for measuring the magnification of an optical beam path

ABSTRACT

The invention relates to a method of determining measurement-point position data and a device for measuring the magnification of an optical beam path. In the method described, a laser beam is inserted via an insertion element (32a) into the beam path of a microscope. At the end of this beam path, a beam splitter (4c) splits the laser beam off again and directs it on to a position sensor (45a). The point at which the measurement beam is incident depends on the magnification of the beam path optics (8, 13). The final value of the magnification can thus be simply determined. The value of the magnification is important for the user in order to enable the user to make a definite assessment of the area observed. Also described are various related developments and details of the invention.

BACKGROUND

The invention relates to a method of determining position data of ameasurement point and a device for measuring the magnification in anoptical beam path, in particular in a beam path of a surgicalmicroscope.

Surgical microscopes are used by a surgeon for the optical magnificationof the area in which an operation is intended to be carried out. Thereare in principle three different types of surgical microscopes, all ofwhich are meant in the sense of the invention. These are,

firstly

pure optical microscopes, that is to say microscopes which contain onlyoptical and mechanical components, the output being directed to the eye;

secondly

pure video microscopes, that is to say microscopes which have optical,mechanical and optoelectronic components, the optical output of themicroscope being directed exclusively to an optoelectronic imagerecording device (for example a CCD), and the image recorded beingfurther processed exclusively electronically and, if appropriate, beingdisplayed via a display; and

thirdly

mixed video microscopes, which contain constructional features of themicroscopes of the first and second type in common, that is to say thatan output is directed both to an observer's eye and to an imagerecording device.

As a result of the magnification of the area to be operated on, asurgeon loses the direct estimation of size which he/she has in the caseof operations with the unaided eye. This leads to problems primarilywhere specific, previously determined cut depths or cut lengths are tobe observed, or where the surgeon has to keep to specific distancesusing a surgical tool in order to make a precise operation possible.Above all in the case of operations on the brain or in microsurgery,this is often imperative in order to avoid damage to healthy tissue. Inthe case of such operations, the result of the operation (whethercomplete success or death) often depends on fractions of millimeters.Therefore, efforts have been made to determine the areas as precisely aspossible and to permit measurements of sizes. As an example of such aknown construction, reference is made to the German Patent ApplicationDE-A-4134481.

In the DE-A mentioned, a surgical microscope is described in which anexact location determination is intended to be carried out of a specificpoint, generated by means of a laser beam, on an object being observed.For this purpose, a sighting method is proposed in which, by means offocusing and defocusing the microscope, respectively, visual fieldmarkings are brought into coincidence. After this, the exactdetermination of the position of the point on the object is intended tobe possible, in that optical system data are used for calculation. Thesesystem data are intended to be determined, according to the DE-A, bymeans of suitable distance detectors or angle detectors on drive unitsfor the respective positioning of positionable optical components. It isspecifically intended to draw conclusions therefrom about themagnification of the magnification system.

The determination of the magnification is therefore carried outindirectly via the measurement of distances, angles or via sensors whichare connected to positioning devices for optical components, and via asubsequent calculation of the corresponding data.

This is in many cases unsatisfactory and insufficient. The main reasonlies in the fact that both the optomechanical components and themechanical/electrical components (sensors) have tolerances which, undercertain circumstances, change nonlinearly. This results in the risk thatmagnification values determined in this way are wrong and therefore theposition data further determined therefrom are not correct. In theextreme case, such incorrect data could lead to serious errors duringthe work of the surgeon. Such errors are possibly somewhat lessenedby--necessarily provided in accordance with the DE-A--calibrationmeasurements on the patient. However, even these are not indisputableand depend primarily on the human capability of the operator. The knownattempt to register mechanical tolerances of the magnification systemduring the assembly of the microscope and to determine therefrom acorrection curve, which is superimposed onto the current data, isinsufficient to the extent that tolerances may change as a function ofcountless factors, and the correction curves then used are of no help.In addition, the determination of such correction curves is itselfproblematic, above all time-consuming. A corresponding correctionprogram, furthermore, requires additional computing power and, in somecases, reduces the computer speed in the real time area.

SUMMARY OF THE INVENTION

The invention is therefore based on the object of developing a method inwhich the said disadvantages are avoided and position data can bedetermined rapidly and reliably. This object is achieved, for example,by the fact that, during the determination of position data, themagnification of the microscope is in each case measured directly andwhile avoiding use of mechanical elements or mechanical sensors. Themeasured value can then be used, for example in the context of knownsystems or methods, for example in accordance with the said DE-A,instead of the value determined by roundabout ways, for calculating theposition data. Apart from this, such an actually measured magnificationvalue can also be immediately directly used in the--for exampleelectronic or software-aided--magnification change of any other imagedata such as, for example, MRI or X-ray image data, should such imagedata be superimposed on the image data determined from the microscopewith the aid of a known or new system.

With regard to the method for determining position data, reference ismade in particular to the description parts of the mentioned DE-A, whichcount as disclosed within the scope of this description. These are inparticular: column 2 line 13 to column 4 line 5, and FIGS. 2-4 and theassociated description parts. With regard to the possibility ofsuperimposing image data, reference is additionally made to thefollowing Swiss Patent Applications, whose corresponding descriptionpassages and figures also count as disclosed within the scope of thisapplication. These are the applications: CH135/94-3; CH198/94-5;CH949/94-2; CH1090/94-1; CH1091/94-3; CH1092/94-5; CH1525/94-0;CH3890/93-3.

Moreover, the invention is furthermore based on the somewhat moregeneral object of providing a device with which the magnification(positive or negative) can be measured directly in a beam path havingoptical components, in particular in a microscope. The measurement datashould serve for the calculation of position data or else also merelyfor the information of the operator.

This object is achieved, for example, by means of the features describedbelow.

The application of the described features leads to a simple constructionwhich impairs the optical properties of the microscope very little. As aconsequence of the small diameter of a measuring beam, which ispreferably constructed as a laser beam, an insertion element can beconstructed to be very small. Furthermore, it can be arranged in thedirect vicinity of the main objective, with the result that it liesoptically below the perceptibility limit. Known optical sensors such asdiode arrays, CCDs, etc. can be considered as the measuring array, inprinciple a linear extent of the array being sufficient. In principle,all reflective components are considered as the insertion element, suchas beam splitters, mirrors, reflective prism surfaces, etc.

One of the two solutions mentioned and also to be applied independentlyof another objective results from the application of a flat glass diskas a carrier plate for the insertion elements. Such a carrier platemakes it possible to minimize the relevant optical components in termsof their constructive size and to lead them as close as possible to themain objective. The assembly in the mechanical construction of suchcomponents and their fastening device, respectively, also becomesparticularly simple thereby.

According to a special embodiment of the invention, that part of themeasuring beam which passes through the beam splitter for splitting outthe measuring beam is filtered out by means of a narrow band filter, orthe measuring beam is selected in a frequency range such that it remainshidden from the human eye.

The invention can be applied in all the above-mentioned types ofmicroscopes, in the case of video microscopes the resulting image pointalso being able to be removed electronically on the image recordingdevice (e.g. on the CCD). On the other hand, the image recording deviceitself could replace the measuring array, if it is possible to representthe measuring point of the measuring beam resulting therefrom withsufficient contrast and without disturbing the surgeon--for examplesplit out electronically.

The measuring beam transmitting frequency, which is reduced inaccordance with a development according to the invention, reduces anystress on a human eye in another way, without impairing the measuringaccuracy. If required, such a device can also be clocked or synchronizedwith the image recording device and with any reference arrays, etc., inorder to exhibit the optimum efficiency with the lowest interference.Thus, for example, the measuring beam can always be emitted just whenthe image recording device is not ready for the reception of image data.Since the magnification--in the case of a fixed setting of the mainobjective--as a rule changes only as a result of changing the zoomsetting, it may be advantageously sufficient if the measuring beam ineach case is emitted only directly following a change of setting on thezoom--which can be determined by a pick off on the servomotor of thezoom.

A further development of the invention, which can also be usedindependently, if required, provides for a mechanical magnificationindicator which is coupled to the positioning device, for example for azoom, any nonlinearities in the positioning of the optical componentsbeing compensated by means of a cam disk.

The invention is described in particular in conjunction with a surgicalmicroscope. In the widest sense, however, it can also usefully beapplied with any other beam paths.

Within the context of the invention, there are various further methods,types of embodiments and variants thereof, which are identified ordescribed in below and in the figures. Furthermore, following study ofthis application and of the documents cited herein, differentcombinations of the most diverse features of constructions which are notdirectly described herein, and which likewise lie within the context ofthe invention, are evident to those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details and embodiments of the invention emerge from thedrawings, wherein:

FIG. 1 shows the principle of a construction according to the inventionfor measuring the magnification of a microscope beam path;

FIG. 2 shows the principle of a variant of the construction according toFIG. 1 with a conventional display for reflecting in magnificationinformation and/or other image data;

FIG. 3 shows the principle of another variant of the constructionaccording to FIG. 1 with a novel mechanical magnification indicator;

FIG. 4 shows a further variant in relation to FIG. 1 with two parallelmeasuring beams;

FIG. 5 shows the principle of a construction with an exclusively visualmagnification indicator in the optical beam path of a microscope;

FIGS. 6A-6C show three variants of the arrangement of the insertion andsplitting out elements in the beam path of a microscope;

FIG. 7 shows a preferred construction, which combines the teachingaccording to the invention by way of example with the invention inaccordance with the PCT patent application, based on CH1090/94-1;

FIG. 8 shows a detail of an insertion element;

FIG. 9 shows a construction for registering the microscope position inspace;

FIG. 10 shows a detail variant from FIG. 9;

FIG. 11 shows a variant thereof;

FIG. 12 shows a basic diagram of a construction in accordance with theinvention and

FIG. 13 shows a more detailed, self-explanatory basic diagram of asimilar construction.

The figures are described coherently. Identical reference symbols denoteidentical components. Identical reference symbols with different indicesdenote similar or functionally similar components. The invention is notrestricted to the exemplary embodiments shown. Above all, in combinationwith the teachings of the Swiss Patent Applications listed above and theGerman Patent Application listed above, further arbitrary variants maybe shown. They all fall under the disclosure content of thisapplication.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a beam path 60a with a schematically indicated mainobjective 8 and a zoom 13. Upstream of the main objective 8, to the sideof the optical axis 7 of the beam path 60a, a small beam splitter 32a isadjustably arranged as an insertion element. The mounting of the beamsplitter is not shown, since a multiplicity of suitable mountings areknown to those skilled in the art. Facing the input side of the beamsplitter 32a is a laser 56, which directs a measuring beam 57a onto thebeam splitter surface. This is preferably aligned in such a way that thesplit off beam 57a runs at an angle to the axis 7. The beam passingthrough forms a reference beam, which is assigned to a reference array.

Arranged downstream of the beam path 60a is a beam splitter 4c forsplitting out the measuring beam 57a. Its output faces alocation-resolving optoelectronic measuring array 45a, at which thesplit out beam 57a is intercepted.

The measuring principle according to the invention lies in the fact thatthe measuring beam 57a reflected in upstream of the main objective 8arrives at a specific place on the measuring array 45a as a function ofthe magnification in the beam path 60a, said measuring array being ableto be electronically interrogated and correspondingly evaluated.

Since, in the case of this construction, that component of the measuringbeam 57a which passes in a straight line in the beam splitter 4c canfall through the eyepiece 18 into an observer's eye, provision is madehere for the beam 57a to be emitted only occasionally. An intervalswitch 43 which is connected via a connecting line 50a to the measuringarray 45a and via a connecting line 50c to the laser 56, interrupts thebeam emission from the laser 56 continuously, so that the measurementsare carried out only from time to time. This is important when themeasuring beam 57a is either so bright that it disturbs an observer, orthat its power in the infrared range is so intense that damage can occurat the observer's eye under permanent irradiation.

FIG. 2 is different to the extent that, in addition to the componentsdescribed, a servomotor 49a is provided for the zoom 13, and is likewiseconnected via a connecting line 50b to a microprocessor 44b. Thisconnection enables measurements to be reduced to an absolute extent,namely to those cases in which a setting change has been undertaken bythe zoom 13. Disturbances to an observer's eye are thereby minimized.

By means of a color filter 42, which is arranged downstream of the beamsplitter 4c, disturbances for an observer's eye can be completelyeliminated. The filter is preferably of a very narrow band character andjust filters out only the color wavelength of the measuring beam (whichis located, for example, in the infrared range).

The eyepiece 18 could alternatively also be a tube lens for an imagerecording device 9, which can be provided either instead of anobserver's eye or, via known arrangements, can also be fitted inaddition thereto--for example split out via a further beam splitter.

In the case of this special refinement, the beam splitter 4c is alsoused as an insertion part for the image of a display 10b, on which imagedata from a module 47 for image data transmission can be displayed.These are as a rule X-ray image data, MRI image data, or else otherinformation such as medical values relating to the patient, positionvalues of the microscope or else just magnification values of themicroscope, which are obtained via the measuring array 45a, if necessaryfollowing conversion by the microprocessor 44b. This information is fedto the display 10b via the connecting lines 50e and 50g. The connectingline 50f enables the forwarding of the magnification data to the module47 for image data transmission, so that preferably standardized imagedata from other systems, fed in via the input 48, can be supplied,converted to the correct magnification, and sent to the display 10b. Bymeans of this device, the superimposition of image data is especiallyconvenient for a surgeon, since the dimensions will certainly becorrect.

An insertion element 32a with which the measuring beam 57a is introducedinto the microscope beam path 60b can be designed in accordance withFIG. 1 as a beam splitter. However, it can also be designed as a prismor as a mirror in accordance with FIG. 2. The insertion element 32a isas a rule fastened onto a carrier plate 41a.

The construction in accordance with FIG. 3 shows, as an alternative toFIG. 2, inter alia a mechanical magnification indicator which, by meansof cam disk 52 passes on the mechanical positioning data of theactuating drive 49b of the zoom 13c to a pointer 55a for a magnificationindicator 51a or to a disk-shaped magnification indicator 51b. For thispurpose, a purely symbolic mechanical pick off 54 and a coupling 53b areindicated, which can be implemented by means of arbitrary componentsknown to those skilled in the art. The essence of this inventive detaillies in this case in the application of the cam disk 52, whichcompensates for any nonlinearities occurring in the zoom positioning.

In the variant according to FIG. 4, two measuring beams 57a and 57b aretransmitted through the beam path 60d at specific angles to the opticalaxis 7. In this arrangement, insertion element 32a is designed as a beamsplitter to generate the measuring beam 57a in reflection and themeasuring beam 57b in transmission and subsequent reflection at theinsertion element 32c. The relation of the spacing b' measured at themeasuring array 45b to the known spacing b corresponds to themagnification of the beam path 60d.

The specific variant according to FIG. 5 indicates the magnificationvalues directly to an observer, in that a magnification indicator 51c,to which a scale is fitted, is connected downstream of the beam path60e. The observer thus sees through the eyepiece 18 not only theobserved image but also the measuring beam 57a, which moves along thecalibrated measuring scale during magnification changes. It mayoptionally be desirable for the magnification indicator to beconstructed to be at least slightly scattering in the region of themeasuring scale.

Also shown in the illustration as a special feature is an alternativeinsertion element 32b, which essentially comprises an optionallyprismatic carrier plate 41c, in which a mirror surface 32b isintegrated. The carrier plate 41c is shown here as a full surface, butunder certain circumstances a rod-like part, which projects only a shortdistance into the beam path 60e and hence leads to a minimum impairment,is sufficient.

Within the sense of the invention, it is not essential whether thespecified components are arranged exactly in the sequence in which theyare shown in each case. Various variations are conceivable, which maybring advantages in accordance with the desired constructional shape.

As an alternative to the described laser beams, other focused lightbeams are also conceivable, providing these have the same effects withregard to the focusing.

Not shown are possible filters, which are arranged directly upstream ofthe array 45a and the like in order to split out any interfering lightfrom the beam path 60.

According to a further specific refinement, the beam splitter 4c couldalso be constructed as a beam splitter having a beam splitter surface atthe Brewster angle, in order to split out a correspondingly polarizedmeasuring beam 57 completely and to keep it away from the eyepiece 18.Such a construction is preferred where high light intensities arenecessary at the measuring array 45.

If the teaching according to the invention is combined with the teachingof the international PCT patent application--based on the Swiss PatentApplication CH1090/94-1, the result thereof is a preferred, integratedconstruction of a microscope. One example of such a construction isshown in FIG. 7. The statements in the said application which makereference to this example likewise count as disclosed within the scopeof this application (cf. in particular claim 9 in conjunction withclaims 1-8 and claims 10-15, and FIGS. 1-4 and associated descriptionparts).

FIG. 6a shows the insertion of the measuring beam downstream of the mainobjective 8 via a prism 32 at an angle to the optical axis 7. Dependingon the angle and the magnification, the measuring beam is incident atdifferent locations on the sensor 45 after being coupled out by element4.

According to FIG. 6b, in order to avoid adjustment problems of theinsertion element 32t, two measuring beams are produced, for example viatwo beam splitter surfaces which are arranged at a defined angle to eachother and which produce two physically separated signals on the sensor45.

Given a known angle, the spacing b is a measure of the magnification ofthe optical system. This principle may also include the main objectivefor determining the overall magnification, if the coupling in takesplace upstream of the main objective 8.

FIG. 6c shows, as a further exemplary embodiment of an insertionelement, a wedge 32k with the beam splitter surfaces 32v and 32w, forexample with 4% reflectivity in each case. In this exemplary embodiment,the beam courses are selected such that they lie symmetrically withrespect to the optical axis 7 following the reflections at the wedge32k.

FIG. 7 shows a laser 56, whose beam 57a is deflected via an adjustablebeam splitter 32a into the microscope optics 8, 13. From the microscopeoptics 8, 13 the beam 57a passes via a beam splitter 4c to a measuringarray 45a. In order to determine the magnification or, respectively, theposition of the focal plane, the beam positions on the measuring array45a are used. In order to minimize possible disturbances emanating fromthe measuring beam, the laser 56 is controlled via an already mentionedabove interval switch 43. The evaluation of the position data is carriedout in a microprocessor 44a. The components described above areconnected to one another by means of connecting lines 50a, c and d.

Already mentioned above distance determination is carried out via adistance measuring system 69, from which optical fibers lead to the endpieces 63 and 63'. Laser light is used, the signal 57c from which is fedin between the object and the microscope toward the first deflectingelement 61. The beam reflected at the object detail 22a is deflected bythe second deflecting element 65 toward the fiber-optic end piece 63'connected to the sensor. The distance measuring system 69 is connectedto the processor 44a, with the result that the latter can determine realpositions on the image section under examination from the distancevalues and the magnification values.

As has already been indicated in FIGS. 2, 4 and 5, the invention alsorelates to a device--which, if appropriate, can also be usedindependently--for the arrangement of insertion elements, reflecting-inelements, splitting-out elements and reflecting-out elements in anoptical beam path in accordance with FIG. 8. In the area of photographyand microscopy, there are often problems with the fastening of opticalcomponents for reflecting specific information into or out of an opticalbeam path. In the area of microscopy, there are more recent developmentsin which laser beams or the like have to be transmitted through the beampath.

For this purpose, beam splitters are known, which are inserted into thebeam path and are shown by way of example in FIGS. 1, 3, 6 and 7.However, these enlarge the constructional volume severely and swallowlight in an undesired manner.

These problems have not yet been satisfactorily solved. This aspect ofthe preferred refinement therefore forms the basis of the objective ofproviding a device which makes possible the insertion and splitting outof small ray bundles in an imperceptible manner and without severelyinterfering with the beam path.

Special embodiments of the invention primarily facilitate the reductionof the constructional size of surgical microscopes.

Such an arrangement therefore leads to more compact beam paths andmicroscopes, respectively.

Within the context of the invention, furthermore, there are varioustypes of embodiments and variants thereof which result from thecombination of the features mentioned here with features from subsequentpatent applications, which place other aspects of an inventive novelmicroscope under protection, said microscope also being equippedprecisely with the arrangement described above. These are the patentapplications already mentioned. Above all, this detail is advantageousfor use for magnification and distance measurement.

Further details and embodiments of the invention emerge from FIG. 8. Thefigure shown there shows the essence of this invention.

A thin glass plate, possibly antireflection coated, carries one or moresmall insertion elements which can be pushed close to lenses, mainobjectives, etc. in such a way that they cause only partial--as a rulenegligibly small--disturbances.

A preferred embodiment of the device according to the invention thuscontains a device for the interference-free insertion of narrow bundlesof rays into optical beam paths. For this purpose, optical insertionelements 4 are fastened to thin glass panes 41, which are inserted intothe beam path directly upstream of lenses.

A further preferred variant of the invention, which enables the positiondata of the measurement point to be determined absolutely in space,results from the use of an arrangement, which can also be usedindependently, in accordance with the features of at least one of FIGS.9-11, respectively.

The position determination of the microscope is in this case undertakenin order to decide on the exact location of the operation field,observed through the microscope, from the setting data of the microscope(focus, zoom, etc.) with simultaneous knowledge of the position of apatient in space. This is becoming more and more important in modernmicrosurgery (stereotaxy), since a surgeon is thus enabled to find withgreat certainty the location at which the operation must be carried out.Conversely, it is possible in this manner to track precisely at whichlocation the operation is being carried out. The significance of suchknowledge is increasing with the advancing technology of makingdifferent diagnostic image data, for example X-ray, CT or MRI imagedata, visible in a microscope beam path, or superimposing them on theimage seen, so that the surgeon can also make use of correspondingcomparative information--shown correctly in terms of location.

The position determination of the microscope (in the sense of theinvention, an endoscope can therefore also be meant) is carried out inaccordance with the prior art using the various techniques. On the onehand there are microscope carrier frames which have measuring elementsin their joints--similar to a robot arm from the machine industry--whichcontinuously simultaneously track the position changes of the microscopeand determine the respective position in space via a microprocessor. Onthe other hand, there are also microscopes and endoscope tips whichdetermine the respective position with the aid of ultrasonictransmitters and sensors which are arranged on the microscope. In thecase of endoscopes, operations are occasionally also carried out under apermanent X-ray beam, in order to be able to determine the position atleast in an optically visible manner.

In the case of a novel development of the applicant, the ultrasonictechnique is dispensed with and use is made of an infrared positioningsystem in which three infrared transmitters with encoded transmissionsignals are arranged on the microscope, the signals from which aredetected by infrared receivers arranged in the operating theater. Thistechnique allows a more exact position determination than by means ofultrasound, since primarily interfering influences can also be excludedand simultaneous working with ultrasonic devices--as may occur in thecase of operations in the region of the brain--is not contraindicated.

In the case of all the previously known position determining methods, inspite of fundamental operational reliability of the methods, twoproblems have to be considered: the patient should not be influenced bythe position determination and any measurement results in the area ofthe operation location should not be influenced by the positiondetermining method.

These problems have not been satisfactorily solved. The specificrefinement is therefore based on the object of providing a surgicalmicroscope with a position determining system which influences neitherthe patient nor any measurement results from the area of the operationlocation (for example brain current measurements).

This object is achieved by means of using sound and current-independentposition transmitters on the surgical microscope such as reflectorshaving specific reflection properties on the surgical microscope, bywhich the signals from a transmitter are detected by the receivers in areflector-specific manner.

In this case, preference is given to the construction using infraredtransmitters which, arranged remote from the surgical microscope, areexcited by means of power, the light pulses emitted by them beingconducted as far as the microscope by means of glass fibers, in orderthere to leave the glass fiber ends and--as in the case of thearrangement using IR light-emitting diodes on the microscope--to beregistered by the sensors in the room and to enable a correspondingposition determination.

Special embodiments of this variant primarily facilitate the reductionof the constructional size of surgical microscopes.

This arrangement thus leads to more compact surgical microscopes, whoseposition in space can be determined simply, without interferingultrasonic signals, power flows or electromagnetic fields. It is thuspossible for the surgeon to work in a more patient-friendly and morelocationally precise manner.

Within the context of the invention, furthermore, there are varioustypes of embodiment and variants thereof which result from thecombination of the features mentioned here with features of the patentapplications mentioned, which place other aspects of an inventive novelmicroscope under protection, said microscope preferably also beingequipped precisely with the arrangement described above.

The principle of this variant is illustrated in FIG. 9: A plurality ofperipherally arranged light-emitting emitting diodes 93 transmit encodedlight pulses which are led to the microscope 82 via glass fiber lines94. The light pulses emerge from the ends 95 of the glass fibers 94 andcan thus be registered by IR sensors 96 arranged in the room. Theincoming pulses are then fed via feedlines 99 and evaluated by anevaluation unit 85 and the position of the microscope 82 is determinedin this way. The evaluation unit 85 is connected to a data conditioningunit 89 or, if appropriate, directly to a computer 90. The evaluationunit 85 may drive the light-emitting diodes 93 via a feedback connection98. The microscope 82 contains an objective 8 and a beam path 60. It isheld via a microscope stand 97.

In the variant according to FIG. 10, only the light from a singlelight-emitting diode 93d is used, which nevertheless emits light pulsesalternately having different light colors. This is carried out, forexample, by varying the feed voltage of the light-emitting diode 93d.Arranged at the microscope end of the glass fiber 94d are two beamsplitters 4c1 and 4c2, which split the incoming bundle of light intothree measuring bundles. These are in each case let through by suitablenarrow band color filters 42 only to the associated glass fiber ends 95,by which means a spatial separation of the outgoing light pulses ispossible.

Corresponding color filters 42 are connected upstream of the IRreceptors 96, with the result that these also in each case respond onlyto the light pulses intended for them.

FIG. 11 shows a variant in which the glass fiber lines are dispensedwith, in that both the light pulse transmitters 93 and the IR receptors96 are arranged in the room and only reflectors 100, each having a quitecharacteristic reflection property for a specific light color, arefitted to the microscope 82, color filters 42 being connected upstreamof said reflectors, with the result that only the corresponding lightcolor is incident on them and can leave them once more. In a somewhatmore complex evaluation method, the position determining unit 85 can inthis way determine the position of the microscope.

It is of course also possible for the feedlines 99 to the IR receptorsto be formed as glass fibers, in order that the room as a whole beintended to be subjected to less electromagnetic fields.

A preferred embodiment thus relates to an arrangement for determiningthe position of a surgical microscope 82 with the aid of frequent lightpulses, which originate from the microscope 82 and are received by lightreceptors 96, glass fibers being arranged between light-emitting diodes93 and the transmitting location 95 of the light pulses, so that thearea of the microscope is free from interfering electric andelectromagnetic waves.

A further preferred development of a device for carrying out the methodaccording to the invention, which can also be used independently of thelatter, comprises an arrangement for data processing for a microscope,for example a video microscope, provided that the latter is connected toan electronic data processing unit and/or a display.

The arrangement for data processing is in particular to be understood asany complete or modular device which is used in conjunction with amicroscope or in conjunction with examinations carried out on amicroscope in order to process data which are of significance for theoperation or for the knowledge from the microscope or for the work underthe microscope. The data processing unit is, for example, to beunderstood to include microprocessors, computers or work stations, withthe aid of which, for example, data from the microscope can beregistered, position data of the microscope can be registered andoptionally further processed or forwarded, or with the aid of which themicroscope is, for example, itself driven.

A display in the sense of the invention is to be understood to include,for example, monitor screens, cathode ray tubes, etc., on whichinformation for a user can appear. Such displays can be arranged bothoutside the microscope, for example as a computer monitor screen, orelse can be constructed as small displays which are connected to theoptical beam path of the microscope such that a user obtains both anoptical awareness from the optical beam path and also, simultaneously(superimposed), an optical awareness from the display.

In special cases, a display may also be understood to include in thewidest sense an acoustic information device.

Video microscopes in the sense of the invention are microscopes havingat least one optical beam path and at least one image recording devicefor the recording and display of an image, seen via the beam path, on adisplay. In recent times, video stereo microscopes, in which twoparallel beam paths are provided and a 3 D image can be displayed on thedisplay, have become a very frequent type of video microscope. Videomicroscopes are often used as surgical microscopes; all othermicroscopes and endoscopes which have the abovedescribed devices alsolying within the context of the invention.

Above all in the case of surgical microscopes and, in particular, duringan operation, a quantity of information accrues which may be of greatsignificance for the surgeon. This is, for example, information aboutspecific parameters of the microscope. However, this is also informationabout the position of the operation field being observed, informationabout the patient or his/her state of health or, respectively, his/herparameters such as pulse, blood pressure, blood oxygen content, etc.and, for example, also comparative data from earlier microscoperecordings made via video or recordings from other recording methodssuch as X-ray, ultrasound, positron beam or MRI recordings.

In addition to this information, a quantity of control data also accrueswhich, for example, are output by the surgeon arbitrarily via controlelements such as a computer mouse, foot switch, etc. to the dataprocessing unit or to control elements for the microscope, in order tocontrol the latter as required, for example to focus it.

Above all in the case of those applications where images aresuperimposed, be it optically or optoelectron-ically, for example bymeans of displays which are reflected via beam splitters into theeyepiece beam path, or purely electronically, for example by means ofimage processing and simultaneous representation of superimposed imageson a display, a problem occurs in connection with the electronic dataprocessing: during operations the surgeon relies on the one hand on areal time display and on the other hand on a rapid reaction of controlelements of the microscope and on exact positioning of the microscope orits field of view.

In the case of conventional constructions, this means that enormouslylarge computer powers are required of the data processing system. Thiscomputer power is used up by the recording and storage of data,conversion of the same into other data, conversion of data from analogvalues into digital values or vice versa, optional comparison of storedor parallel recorded data with recorded data and the output of data tocontrol elements, displays, indicators, data networks and so on. At thesame time, it is also necessary in the electronic data processing toload various software programs which make mutual interlinking necessary,which is often complicated and correspondingly expensive.

U.S. Pat. No. 5,073,857 describes a method and a device for a cellanalysis which, inter alia, has a video camera, an image generator, amicroprocessor, a counting device, a comparison device, a digital/analogconverter, a control device for the microscope and a computer. Thecomputer is in this case provided only as an extended input/outputdevice for the microprocessor and the latter is assigned a programmemory, with the result that it can be viewed for itself alone ratherthan as an actual computer which in turn requires the said high computerpower in order to enable working in real time.

By contrast, the preferred development is based on the object ofproviding an arrangement for data processing or a microscope with suchan arrangement in which it is possible to work with the most rapidprocessing times in real time and in which the required computer powerin the data processing system itself can be kept small. In terms ofsoftware, too, it is intended to provide a compact construction withsimple expansion capabilities.

This object is achieved by means of the application of the featuresdescribed herein. This embodiment as a whole represents an arrangementwhich is comparable with a human; sense organs and extremities areconnected via the spinal cord, which itself fulfills specific functions,with the brain (computer).

As a result of the arrangement according to the invention, all the dataof interest are continuously and automatically conditioned in such a waythat the connected computer (in many cases a work station) has access tooptimum and standardized data formats which are determined andconditioned irrespective of its computer power. The computer does nothave to carry out all the computing operations, as was previously thecase; its EDP power can be restricted to the computing operationsprovided in each case to be calculated in its main memory, as a resultof which it can itself be laid out in an optimum manner. The real timebehavior required by the users can be achieved simply by means of theinvention.

Particular embodiments of the arrangement. In the case of theirapplication in the surgical microscope field, they primarily facilitatethe mode of operation which is specific to the user in each case.

The arrangement according to the invention thus leads to microscopes ormodes of operation using microscopes which are more compact, faster andmore reliable for the user, which is primarily of enormous advantage inthe field of microsurgery.

Within the context of the invention, furthermore, there are varioustypes of embodiments and variants thereof which result from thecombination of the features mentioned here with features of the patentapplications mentioned, which place other aspects of an inventive novelmicroscope under protection, said microscope preferably also beingequipped precisely with the arrangement described above. These are thepatent applications: CH949/94-2, CH1525/94-0 and, in particular,CH1090/94-1.

Further details and embodiments of the invention emerge from FIGS. 12and 13.

The principle of this development is clarified in FIG. 12: a pluralityof periphery devices are led together to a data conditioning unit 89 inorder there to condition data for further processing in a computer 90.However, as required the data conditioning unit 89 also converts datafrom the computer 90 into such data formats as can be used immediatelyand directly in the peripheral devices. Specific data, whose processingin the work station is not necessary, can, if required, also be madedirectly available for other peripheral devices following theirconditioning (conversion, format adaptation, linking with other data).

An example may be cited of a desired magnification which is reported bythe user by instruction to the arrangement or to the data conditioningunit 89. The instruction, which is for example a numerical value, iscompared with a measured value of the magnification from the device 85,this being initially, for example, an analog voltage value or a digitallocation vector value, which values are firstly automatically convertedby the data conditioning unit 83 in order to make a comparison betweenthe two desired and actual data items possible. If the comparison showsa difference, then, for example, a corresponding control value for themicroscope control elements 92 is produced in order to enable acorresponding regulation in the manner of a control loop.

Also, for example, patient information data can be brought into view invisible form on a display, corresponding comparative data from adatabase also being displayed on the same display at the same time.Within the context of the invention, such data can, for example, also beconditioned without making any demand on the computer power of thecomputer 90. This is thus available for more complicated computingmanipulations, for example for converting MRI image data for enlargingor diminishing the MRI image in accordance with the set magnificationvalues in the microscope beam path 60 and for the image-processingsuperimposition of the MRI image on the image being viewed through themicroscope beam path 60 and being recorded, for example by means ofvideo camera 9, the completed superimposition being displayed for theuser on a display 10a and/or 10b.

The statements in accordance with FIG. 13 are self-explanatory to thoseskilled in the art.

A microscope 82, which is connected to various peripheral devices suchas device 83 for the automatic, electronically aided magnificationmeasurement through the microscope optics 60, device 84 for theautomatic, electronically aided distance measurement between the objectbeing observed and microscope 82, device 85 for the automatic andelectronically aided determination of the position of the microscope 82in space, device 88 for driving position change drives of the microscope82, database, video camera, device for registering patient data such as,for example, name, pulse, blood pressure, blood oxygen content, etc., isconnected to a data conditioning unit 89 which conditions or convertsdata in the correct format before they go into a connected workstationor when they emerge therefrom, in order to enable real-time operationwith relatively low computer powers in the work station.

List of Reference Symbols

This list of reference symbols also contains reference symbols fromfigures which are contained in the abovementioned Applications, sincethese reference symbols, or the features cited by means of thesereference symbols and their corresponding description and drawing parts,count as simultaneously disclosed for combination purposes within thescope of this invention. In particular, this relates to the microscopeshaving specific beam paths and beam splitters and to the devices formeasuring the magnification and the distance of the microscope from theobject.

1 first beam path; a,b

2 second beam path (geometrically superimposed first beam paths); a,b

3 mechanooptical switching element

3a-c opaque and preferably silvered aperture diaphragm

3d LCD shutter element

3e micromechanical lamellar mirror construction

3f LCD alternating shutter element

4 beam splitter

4a,b beam splitter

4c beam splitter for splitting out measuring beam 4c1, 4c2

5 disk

5a semicircular area

5b remaining area of the disk 5

5c circular segment areas

5d

6 axis for disk

7 central axis

7a,b central axis

8 main objective

8a main objective

8b main objective exchangeable with 8a (different focal lengths)

9 electronic image recording device

10 display

10a display

11 mirror; a,b

12 positioning device; a-c

13 zoom

14 motor; a,b

15 reciprocating drive

16 feed line

17 light source

18 eyepiece

19 deflecting mirror

20 push rod

21 rigid mirror

22 object

22a object detail

23 plane plate; a-d,a',b'

24 pivoting drive

25 linkage

30 lamellar mirror of 3e

31 tube lens

32 insertion element

32a beam splitter

32b mirror

32c second insertion element

33 magnification optics

34 arrows

35 further mirror

36 actuating drive

37 beams

38 deflecting mirror; a,b

39 retro prism

40 balance weight

41 carrier plate a,b,c: prismatic with integrated mirror

42 color filter; a-f

43 interval switch

44 microprocessor

45 measuring array a

46 reference array a

47 image data transfer module

48 external image data input

49 servomotor for zoom 13; a,b

50 connecting lines a-g

51 magnification indicator a-c

52 cam disc

53 coupling

53a between servomotor 49b and zoom 13 and/or between 49 and 52

53b between cam disk 52 and magnification indicator 51b

54 mechanical pick-off

55 pointer; a,b

56 laser

57 measuring beam a-c, c1

58 reference beam

59 arrows for displaceability of the insertion element 32

60 microscope beam path a-e

61 first deflecting element a

62 focusing element a,b

63 optical fiber end piece a,b

64 light source a

65 second deflecting element

66 sensor

67 distance range a

68 connecting line

69 distance measuring system

70 connection

71 magnification measuring unit

72 position determining system a,b

73 interferometer

74 semitransparent mirror

75 reflector

76 detector

77 electromechanical positioning element

78 interferometer control

79 grating

80 detector CCD

81 stages

82 microscope

83 arrangement for measuring the magnification of the microscope

84 arrangement for measuring the distance between object and microscope

85 position measuring system for determining the absolute position ofthe microscope in space in order also to be able to infer therefrom theposition of the field of view on the object in accordance with knowledgeof the distance

86 toolbox for various user programs

87 command control element (computer mouse)

88 command control element for movement control of the microscope (e.g.foot switch)

89 data conditioning unit

90 computer (workstation)

91 control switch for microscope

92 electromechanical control unit for microscope (zoom, focus etc.)

93 light-emitting diodes; a-c

94 glass fibers; a-c

95 ends of the glass fibers; a-c

96 IR receptors; a-c

97 microscope stand

98 feedback

99 feed lines; a-c

100 reflectors with special surface

b spacing between the measuring beams 57a and 57b

b' spacing between the measuring beams 57a and 57b at the measuringarray

d1,2 stereo base

We claim:
 1. A method of determining position data of a measurementpoint on an object being observed through a microscope, in whichposition data of the microscope and data about a focal plane and amagnification data of the microscope are determined and position dataare subsequently calculated therefrom, wherein the magnification dataare measured directly with the aid of at least one optical measuringbeam (57a, 57b), which comes from outside and is inserted at least intozoom optics (13) of the microscope and passes through the latter, fromdeflection of the measuring beam (57a, 57b) and inserted into acalculation for determining position data.
 2. A method according toclaim 1, wherein measurement is carried out by means of opticaldeflection of at least one visible measuring beam (57) by microscopeoptics (8,13), the measuring beam (57a) lying in the visible wavelengthrange and the measuring beam (57a) being assigned a measuring scale(51c) which is visible to an observer and on which the observer can readthe magnification value directly.
 3. A method according to claim 1wherein measurement is carried out by means of optical deflection of atleast one measuring beam by microscope optics (8,13) onto a mechanicallydefined optoelectronic location-resolving measuring array (45) whoseelectronic output values correspond to the magnification.
 4. A methodaccording to claim 1, wherein measurement is carried out by opticaldeflection of two measuring beams (57a,b) located at specific angles toan optical axis (7) of the microscope by microscope optics (8,13) ontoan optoelectronic measuring array (45b), whose spacing (b) is known, thespacing (b') of the deflected beams (57a,b) from each other or theelectronic output values resulting therefrom corresponding to themagnification.
 5. A device for measuring the magnification in an opticalbeam path (7) in a microscope having microscope optics (8,13), having atleast one laser (56) for producing at least one measuring beam (57) andat least one magnification indicator wherein connected downstream of thelaser (56) at least one insertion element (32) is provided via which themeasuring beam (57) can be steered through the microscope optics (8,13),and connected downstream of the microscope optics (8,13) at least onecalibrated magnification indicator (51c) is provided on which themagnification may be read or at least one beam splitter (4) is provided,on which the magnification can be read off or at which the measuringbeam (57) can be split off and fed to a measuring array (45), electronicoutput values from the measuring array (45) corresponding to themagnification.
 6. A device as claimed in claim 5, wherein the measuringbeam (57) is split by an insertion element (32a), which is a beamsplitter, into two measuring beams (57a,b), which are reflected via theinsertion element (32a) and via a second insertion element (32c) intothe beam path of the microscope and, via the beam splitter (4c), ontothe measuring array (45b), the spacing (b) between the two measuringbeams (57a,b) being defined and the spacing (b') between two measuringbeams (57a,b) at the measuring array (45b) corresponding to themagnification.
 7. A device according to claim 5, characterized in thatthe insertion element or elements (32) are arranged or constructed on aflat, transparent carrier plate (41a) which is built into the beampath--if appropriate, interchangeably--parallel to the main objectiveplane and upstream of the main objective.
 8. A device according to claim5, characterized in that the measuring beam (57) can be produced in alaser (56) whose wavelength lies in the invisible range and whose outputpower lies below an intensity which is damaging to the human eye, and/orin that--considered in the direction of the measuring beam through themain objective--a color filter is arranged downstream of the beamsplitter (4c) for splitting off the measuring beam, a very narrow bandfilter effect of said color filter filtering out the color frequency ofthe measuring beam.
 9. Device according to claim 5, characterized inthat the measuring beam (57) can be output in a cyclic mannerintermittently and/or using the measuring array (45) and, ifappropriate, using other opto-electronic or electromechanical componentsof the microscope.
 10. Device according to claim 5, characterized inthat the magnification value of the microscope optics which isdetermined at the measuring array (45a) is fed back or displayed via adisplay (10b) in a form suitable for an observer, the display (10b)making use of that same beam splitter (4c) for splitting out themeasuring beam (57a) for inserting the display image.
 11. Deviceaccording to claim 5, characterized in that the image of a display canbe inserted into the observation beam path via the beam splitter (4c)for the measuring beam (57), the display (10b) being coupled for thispurpose to a module (47) for image data transmission, which is furtherconnected via a microprocessor (44b) to the measuring array (45a) and,makes available image data, adapted in accordance with magnification,from other image data sources (48).
 12. A device as claimed in claim 5,wherein at least the beam splitter (4c) for splitting out the measuringbeam (57) is constructed as a mechanooptical switching element whoseswitching state alternates between a transmissive and a reflectivestate.
 13. Device according to claim 6, characterized in that smalloptical insertion elements (for example beam splitters) (4) are arrangedor constructed on a thin carrier disk (41), which is inserted into thebeam path.
 14. Device according to claim 13, characterized in that thecarrier plate (41) is arranged in the direct vicinity of objectives orlenses.
 15. A device as claimed in claim 13, wherein the opticalinsertion elements (4) are arranged in the beam path of a surgicalmicroscope.
 16. A device according to claim 8, wherein said color filteris a Fabry-Perot filter.